When Lanny Davis is arguing in favor of a genuinely progressive policy, you know there’s been a sea change around it. Similarly, when Bernie Sanders, Barbara Boxer, Mary Landrieu and Evan Bayh sign a letter promoting the same policy, something’s odd. And that’s the case with Ron Wyden’s Free Choice Amendment, which would open the insurance exchanges to more than 10% of the population by allowing those who currently get coverage through their employer to participate in them, and potentially the public option.

Wyden is a persistent presence on cable news, and the media generally respects his opinion on health care (particularly as residual benefit from the bipartisan Wyden-Bennet proposal from years past). In addition, his skillful use of choice and competition to usher in a progressive policy that would really change the nature of the health care market has attracted a bipartisan set of admirers. Now he’s assembled an interesting group of Senators to push Harry Reid to accept a version of his Free Choice Amendment in the final Senate health care bill.

We are concerned that under current proposals too many Americans will not be able to purchase insurance in the exchanges. To function properly, these markets will need to be robust enough to reform insurance industry behavior to hold down costs and improve quality. To ensure that health reform promotes real competition among insurers, we support a version of Senator Wyden’s Free Choice proposal to expand consumer choice by opening up the exchanges.

Based on the letter, the “version” of the Free Choice proposal on offer here would do everything the regular proposal does, while exempting those individuals who receive their health coverage through a collective bargaining agreement. By keeping the unions in the employer market while allowing everyone else the freedom to choose employer coverage or the exchanges, Wyden gets around the political problem of the unions wanting to keep their benefits, while still really changing the nature of how most people could get their insurance, and moving toward forcing the insurers to really compete on price and quality of service.

I get Boxer, Kaufman, Cantwell, Sanders and even Burris. But Mary Landrieu? Evan Bayh? Bill Nelson? Clearly the rhetoric of choice can bring together extremely diverse elements of the Democratic Party.

Wyden has been among the cagiest lawmakers in Washington when it comes to health care, and if his determination to open the exchanges pays off, we could see a really transformative bill.